Ferroelectric dielectrics such as barium strontium titanate (BST) have been suggested as capacitor dielectrics (DRAM storage capacitors or coupling capacitors in general circuits) in submicron integrated circuits because of their high dielectric constant. In addition, materials such as lead zirconium titanate (PZT) or strontium bismuth tantalate (SBT) that can store charge permanently may be used for non-volatile memories.
Their chemical properties, e.g. reactive nature, require that they be used with noble metals such as Pt or Ir.
These metals, however, are difficult to process by conventional reactive ion (dry) etching.